spl: make SPL and normal u-boot stage use independent SYS_MALLOC_F_LEN

Some platforms have very limited SRAM to run SPL code, so there may
not be the same amount space for a malloc pool before relocation in
the SPL stage as the normal U-Boot stage.

Make SPL and (the full) U-Boot stage use independent SYS_MALLOC_F_LEN,
so the size of pre-relocation malloc pool can be configured memory
space independently.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
[fixed up commit-message:]
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/common/Makefile b/common/Makefile
index 17a92ea..60681c8 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -139,9 +139,11 @@
 endif
 obj-$(CONFIG_CROS_EC) += cros_ec.o
 obj-y += dlmalloc.o
-ifdef CONFIG_SYS_MALLOC_F_LEN
+ifdef CONFIG_SYS_MALLOC_F
+ifneq ($(CONFIG_$(SPL_)SYS_MALLOC_F_LEN),0)
 obj-y += malloc_simple.o
 endif
+endif
 obj-y += image.o
 obj-$(CONFIG_ANDROID_BOOT_IMAGE) += image-android.o
 obj-$(CONFIG_$(SPL_)OF_LIBFDT) += image-fdt.o